So I wrote out the math to help with this. Turns out when looking at just the value, it actually has the least profit of the three between the keg and preserves jar for both high and low value fruit. This is following: value*3 for the keg, (value*2)+50 for the preserves jar, and ((value*7.5)+25)/5 for the dehydrator to find the per fruit profit.
Ancient Fruit
keg-1650g
preserves jar-1150g
dehydrator-830g
Salmonberry
keg-15g
preserves jar-60g
dehydrator-12.5g
I think that even though it has the least per fruit value, it does produce much quicker and can use mushrooms, so would be a good use for any overflow you have while waiting for the keg and the jar to cook.
Thank you for coming to my ted talk